As with most of WoW story each expansion, it need ignoring previously established plot points and surround certain NPCs in plot armor to make it function.
Impressive clans that was capable of holding back both the Alliance and the Horde. (Another inane lore point: Two clans , also maghar orcs (?), that can muster the numbers to actually give the horde pause at the gates, which according to the lore had the majority of the orcs)